302
FXAK68 PAFC 032346
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
346 PM AKDT Mon Jun 3 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Tonight
through Thursday afternoon)...

Showers will continue to taper off the rest of the evening as
shortwaves and associated lift over the area weaken. However,
there could be a lightning strike or two in portions of the
Northeast Copper River Basin, especially near Mentasta Lake before
showery activity wanes overnight.

The low in the gulf will reposition to the east-central Gulf by
Tuesday. The upper-low will help to drag an easterly wave out of
Canada into Southcentral Alaska through Wednesday. The result will
be widespread rains starting first in the Copper River Basin
Tuesday night and working westward across the rest of Southcentral
to the Susitna Valley by mid-day Wednesday. Overall, have
generally increased precipitation amounts as this wave works
westward Tuesday night through Wednesday. The highest amounts will
still favor the Northern Gulf Coast and Prince William Sound
communities where upslope enhancement will provide greater lift to
wring out more moisture.

Confidence continues to be low on the track of the low after
Wednesday which will have an impact on how much precipitation
Kodiak Island receives Wednesday night into Thursday. However,
confidence is greater with the continuation of favorable southerly
to southeasterly flow into the Northern Gulf Coast, Prince
William Sound, and the Eastern Kenai Peninsula. This will promote
a continuation of rainfall for communities such as Seward, Valdez,
Whittier, and Cordova Wednesday evening through the day Thursday
as weak shortwaves lift northward through the southerly flow.

&&

SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THE
ALEUTIANS (Days 1 through 3)...

A persistent low pressure system in the Gulf of Alaska maintains
its influence, driving easterly shortwaves across Southwest
Alaska, promoting shower activity throughout the region through
tomorrow. Convergence of the easterly waves and the advancement of
an approaching trough continues isolated thunderstorms across the
Kuskokwim Valley, the Western Alaska Range, and interior Bristol
Bay through late this evening.

An arctic upper low is poised to track south over the Bering and
Pribilofs through Wednesday, ushering in an anomalously cold
airmass with it. A shortwave originating out of eastern Russia on
the western periphery of this upper low will spawn a surface low
that skirts just west of the Pribilofs tomorrow. This low,
however, will bring a period of rain showers to the central
Aleutians Tuesday night into Wednesday, with rain and snow showers
still expected for the Pribilofs on Wednesday as the main upper
low and arctic airmass moves south. Unsettled conditions
characterized by scattered showers are likely to persist through
at least Thursday as the upper low meanders around over the
Aleutian Chain, with high temperatures not making it out of the
upper 30s to lower 40s.

Mainly dry conditions are expected for much of Southwest Alaska
on Wednesday as a shortwave ridge builds in. Precipitation chances
return to portions of Southwest Alaska Wednesday night into
Thursday as a low over the Gulf pushes inland over Southcentral
Alaska, sending easterly shortwaves and subsequent precipitation
over the region.

-ME

&&

.LONG TERM FORECAST (Days 4 through 7) Friday through Monday...

A generally unsettled pattern remains for much of southern Alaska
for the beginning of the period as a large upper low sits over
the Bering. Through the period, this low will pull another upper-
level low up from the North Pacific, into the Gulf of Alaska. At
the surface Friday morning, a rainy pattern across mainland
Southern Alaska is expected, with models advertising varying
levels of intensity. However, by Saturday morning the showers are
expected to ease across the area, while a surface low pressure
system builds and moves into the Gulf of Alaska. Generally, this
system will maintain the unsettled pattern across the Southcentral
coastline this weekend.

More specifically, deterministic model solutions by early this
weekend disagree regarding the location of the surface low, and to
what degree it influences the Southcentral coastline. The GFS/EC
solutions bring the precipitation into Kodiak Island as early as
Saturday afternoon, while the Canadian solution keeps it in the
eastern Gulf of Alaska near Sitka at that time. Model solutions
continue to diverge beyond Saturday afternoon, leading to low
confidence regarding the timing and intensity of escalated rain
impacts.

-CL

&&
.AVIATION...

PANC...VFR conditions expected to prevail through the period. May
see a period of Turnagain arm winds develop and bend into the
terminal late this afternoon and evening before decreasing and
gradually veering to more southwesterly by Tuesday afternoon.

&&


$$